Counterterrorism, Investigative Detention, and the New Global Security Environment

by | Sep 2, 2021

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The images of Afghan civilians clinging to crowded military planes departing Afghanistan as the Taliban reclaimed Kabul are the iconic indicia of a tectonic shift in the global security environment. This shift, to be sure, did not begin with the U.S. retrograde from Afghanistan. Rather, it is part of a larger trend manifesting itself in a kind of global force realignment as the United States and other international partners reduce their presence in key battlefields such as Iraq, Syria, and the Sahel. In this new operating environment, the world will continue to face threats from terrorist organizations, but it will be forced to confront them differently. As soldiers leave the battlefield and return to garrison environments, decisionmakers will find their supply of battlefield solutions to be somewhat constrained. New approaches under different legal paradigms will need to be formulated and implemented. Specifically, the new global security environment will require a greater reliance on law enforcement authorities for major counterterrorism efforts.

One area that will be of acute interest in this regard is detention. Detention is among the most invasive and potent exercises of government power over an individual. It entails the assertion of control over the body of a person who is, thus, deprived of the most basic freedom to do as they want without hindrance or restraint. Detention occurs on the battlefield (in the military context) as well as on the streets (in the law enforcement context), though each operates pursuant to different constituent theories and—not surprisingly—each is governed by very different legal frameworks. Battlefield detention is regulated by the law of armed conflict. Law enforcement detention, in contrast, is governed by the domestic legal regime of the detaining government authority and, to varying degrees, international human rights law. Both contexts are important for a fulsome understanding of counterterrorism operations, though law enforcement detention will certainly now ascend in importance as battlefield options diminish.

On that score, a powerful tool that is used by many law enforcement authorities around the globe is investigative detention—the pre-charge detention of a suspect for the purpose of obtaining evidence for use at a subsequent criminal prosecution. This differs from other kinds of detention that are relevant to counterterrorism operations (such as battlefield detention under the law of armed conflict) in that it is a detention power that exists within the ordinary, domestic criminal law frameworks of various jurisdictions (such as France and the United Kingdom). Investigative detention permits law enforcement authorities to proactively seize an individual and hold that person for the purposes of disrupting criminal activity, conducting an interrogation, obtaining evidence, and ensuring the integrity of an ongoing investigation. It is also the subject of my recent book, Counterterrorism and Investigative Detention: International and Comparative Legal Evolution.

In my book, I explore the international and domestic legal developments related to investigative detention as it is carried out in the United States, the United Kingdom, and France. As part of this discussion, I explain the evolving threat environment that features investigative detention. In this post, I will touch on some of the legal issues illuminated by the book, notably the way in which each legal regime—based on its respective legal tradition and history—shapes the way in which investigative detention is exercised. Relatedly, this post will also highlight the way in which international law has served as a vector for change and convergence among these otherwise divergent legal systems—creating a rough similitude in the evolving approaches of the United States, the United Kingdom, and France to the problems associated with the investigative detention of terrorist suspects.

International Legal Development

Investigative detention is innately controversial due its infringement on basic freedoms. Nonetheless, driven by imperatives of national security and maintaining social order, governments around the world—including liberal democracies—have turned to investigative detention as a law enforcement tool. As a result, both domestic courts and legislatures have had to reconcile this practice with the basic freedoms enshrined in their foundational texts. It has also subjected the concept and practice of investigative detention to international legal scrutiny. This scrutiny has resulted in the formation of new, more precise international norms relating to the detention of a suspect without judicial oversight. Over the last decade in particular, the concept of investigative detention has been the subject of significant international and comparative legal evolution.

Beyond what domestic law permits, it is critical to keep in mind that international law (most notably international human rights law) regulates detention by government authorities in various ways. While investigative detention is not per se violative of international law, there are definite restrictions, limitations, and obligations associated with the detention of an individual for investigative purposes—and many opportunities for detaining authorities to run afoul of limits set by key international human rights law instruments such as the International Covenant on Civil and Political Rights (ICCPR) and the European Convention on Human Rights (ECHR).

Notably, the UN Working Group on Arbitrary Detention has opined that Article 9 of the ICCPR requires that the accused be presented to a judicial authority within forty-eight hours of arrest, “and any longer delay must remain absolutely exceptional and be justified in the circumstances.” The European Court of Human Rights (ECtHR), however, has been somewhat more lenient in its approach. It found in one case, for example, that “the release of [an individual], who was held in police custody for no more than three days, may be regarded as ‘prompt’ for these purposes,” but that, in another case, detention in police custody which had lasted four days and six hours without judicial control violated Article 5 section 3 of the Convention. The most stringent international human rights law standard, therefore, is the ICCPR standard (a maximum of forty-eight hours) and the laxer is the ECHR standard (approximately four days).

A Comparative Synopsis

The jurisdictions chosen for my analysis—the United States, the United Kingdom, and France—are fascinating objects of analysis due to their differences as much as their commonalities. Each represents a different type of democracy, a different type of legal system, and each has had experiences with different types of terrorism. Moreover, the United States and the United Kingdom are generally considered archetypes of common law, while France is regarded as the avatar of the civil law model. Each, however, is also a vibrant democracy that seeks to adhere to international norms, and over the past two decades each has also had to contend with the common terrorist threat emanating from radical Islamist terrorist organizations such as Al Qaeda and the Islamic State of Iraq and al-Sham (ISIS). Accordingly, observation of the way each of these countries has responded to this threat permits an exploration of potential counterterrorism approaches within the context of a liberal democracy. We can evaluate successes, learn from failures, and note trends. Such an observation also illuminates how international law and other factors can shape domestic legal systems.


France adheres to (and is the principal source of) the continental civil law model. Pursuant to this model, criminal procedure is structured as an official inquiry during which the detention of the criminal suspect is a more accepted part of the investigative process. The principal investigative detention mechanism in France is called garde à vue—a tool which permits French law enforcement authorities to arrest and maintain custody of a criminal suspect for investigative purposes. The French investigative detention regime also makes use of other legal mechanisms such as contrôle d’identité and détention provisoire which are explored in greater detail in my book.  This post, however, will focus on the French legal authorities related to garde à vue.

In France, a person generally cannot be kept under garde à vue for more than twenty-four hours. With the permission of the Procureur de la République, however, that period of time can be prolonged (in ordinary cases) for an additional twenty-four hours, to forty-eight hours. Beyond that period, pre-charge detention in garde à vue is placed under judicial control by the juge des libertés et de la detention. Under the aegis of that form of judicial supervision, French law permits the continued detention of a terrorist suspect in garde à vue for a period of up to 144 hours (six days).

It is important to emphasize that this form of investigative detention is regulated and subject to judicial oversight. Persons detained in France (including terrorist suspects) are presented to a judicial authority—the juge des libertés et de la détention—within forty-eight hours of arrest. This meets the more stringent requirements of Article 9 of the ICCPR, and clearly passes muster with Article 5 of the ECHR. Moreover, the array of due process protections now available to a detained person in France—including the right to counsel, more robust assistance than had previously existed in the French system, and the requirement that French authorities notify detained persons of their rights, including the right to remain silent—ensure that French investigative detention is not arbitrary.

Notably, some relatively recent ECtHR jurisprudence (most significantly the case of Brusco v. France) prompted the French Conseil constitutionnel (Constitutional Council) to require that police questioning during garde à vue include more robust assistance from a lawyer than had previously existed in the French system and, moreover, to oblige French authorities to notify detained persons of their right to remain silent. This served to significantly alter the physiognomy of the French legal system. As a result, today the rights given to suspects detained by French authorities resemble those that have long been the hallmarks of common law systems.

The United Kingdom

In the United Kingdom, the primary investigative detention mechanism is generally referred to as “pre-charge detention.” As my book discusses, UK law contains multiple additional authorities relevant to detaining or otherwise incapacitating terrorist suspects such as Terrorism Prevention and Investigation Measures (TPIMS). This post, however, will focus on the rules relating to pre-charge detention.

Under UK law, under ordinary circumstances, a suspect can generally be kept in police detention for up to 24 hours without being charged, though this period can be prolonged. After thirty-six hours, the detained suspect must be released unless charged or unless a Magistrates’ Court has issued a warrant for further detention. UK legislation in force today allows that, in terrorism cases, pre-charge detention can continue for forty-eight hours before police are required to seek a warrant for further detention from a Magistrates’ Court. Thereafter, with appropriate judicial oversight and approval, pre-charge detention can potentially be prolonged for iterative periods of seven days at a time, up to a maximum period of fourteen days. Importantly, however, any pre-charge detention beyond forty-eight hours requires judicial oversight and authority, and in order to prolong detention beyond the initial forty-eight-hour period in the United Kingdom, a police officer of at least the rank of superintendent must apply to a “judicial authority” for a warrant prolonging the period of detention.

As in France, such detention is subject to judicial oversight and control. Terrorist suspects detained in pre-charge detention in the United Kingdom are presented to a judicial authority—a Magistrates’ Court—within forty-eight hours of arrest. It is worth noting that this rule meets the more stringent requirements of Article 9 of the ICCPR and would seem to satisfy the more permissive standards of Article 5 of the ECHR. Likewise, the legacy of due process protections in the United Kingdom—the right to consult a solicitor privately at any time, and the requirement that a person suspected of an offense be advised of his or her rights before questioning—ensures that UK investigative detention is not arbitrary.

The United States

The United States has never comfortably accepted the concept of investigative detention, though the U.S. legal system has seemed to approximate such detention when needed. In the United States, after a warrantless arrest, a suspect must be brought before a magistrate for a determination of whether police had probable cause to effect an arrest. This must be done without “unnecessary delay,” which typically means within 48-72 hours of the arrest. Any confessions or statements made to police officers during the period of time between arrest and a defendant’s initial appearance before a court must generally be excluded. (This is often referred to as the McNabb-Mallory rule). As a result of this rule, the U.S. system—unlike the French and UK systems described above—does not really allow much room for investigative detention.  Although U.S. legislation (The Omnibus Crime Control and Safe Streets Act) carved out a six-hour period during which confessions will not be excluded solely because of delay, nothing in that law or the jurisprudence interpreting it would permit delay in presentment (i.e., continued detention) solely for the purpose of interrogation. And other strong due process protections in the U.S. system—such as the well-known Miranda advisement, the right to remain silent, the right to an attorney, and associated protections—also serve to protect suspects from coercive confessions and otherwise inhibit interrogation during police custody.

Approximations of Investigative Detention Under U.S. Law

There have, of course, been some notable exceptions to the general rule that U.S. law disallows investigative detention. For instance, the public record contains instances of terrorist subjects being captured by U.S. authorities and held on vessels overseas where they were interrogated for days before being brought before a U.S. court.  Examples include the cases of Ahmed Abdulkadir Warsame, Abu Anas al-Libi, and Ahmed Abu Khatallah. In such cases, even the constraints of the McNabb-Mallory rule would permit the use of confessions or statements elicited in much longer periods of pre-charge detention if such a delay is reasonable. U.S. courts have, after all, interpreted these constraints rather expansively in terrorism cases. The Khatallah case is instructive. There the court permitted the use of statements elicited during a thirteen-day delay between Khatallah’s arrest and his presentment before a magistrate judge—a period of time that went well beyond the six-hour safe harbor provided for in 18 U.S.C. § 3501(c). In such moments, U.S. law sometimes seems to approximate a sort of investigative detention because the person is being held for a prolonged time and interrogated without judicial intervention or oversight. Cases involving terrorists apprehended on the high seas, however, are rare, episodic, and the decisions on the legality of their capture and detention are closely tied to exceptional fact patterns.

Other examples of legal tools that approximate investigative detention include the Material Witness Statute, which allows for the prolonged detention of an individual when it can be shown that, based on probable cause, the witness in question has material information relevant to a criminal matter and his or her presence cannot be attained through a subpoena. Additionally, apart from the procedures in U.S. law applicable to suspects who are citizens, there is the regime of law applicable to noncitizens. Under 8 U.S.C. § 1226(a), an alien may be “detained pending a decision on whether the alien is to be removed from the United States.” Detention under § 1226(a) is discretionary; the Attorney General may release the alien on bond or conditional parole (8 U.S.C. § 1226(a)(2)). Section 1226(c) of the same statute makes detention mandatory where the alien is inadmissible or deportable based on the commission of certain offenses. Like the Material Witness Statute, this section  (in some instances) can be used to harness immigration detention in a way that approximates investigative detention, but it was not built for this purpose, nor is it without some constraints.

Accordingly, U.S. law and jurisprudential rules have provisions that sometimes afford a degree of flexibility to U.S. authorities who may ascertain a need to detain an individual during the course of an investigation. The primordial American aversion to investigative detention, of course, haunts the use of these mechanisms and potentially imperils any investigation in which it appears that the purpose of detention was for investigative purposes—especially when that detention is prolonged. Though exceptions to the ordinary U.S. rules and procedures exist, such exceptions are very fact-specific and dependent upon circumstances that will not be present in every case. For instance, in an era of increasing threats from radicalized “homegrown” extremists, not every suspect will be an immigrant or alien. Likewise, the Material Witness Statute will not be applicable to every suspect. And, as noted, relatively few suspects will be captured overseas and detained on naval vessels on the high seas.

These areas of divergence from the general U.S. rule remain, therefore, exceptional and do not mark a fundamental legal shift. Even so, despite these differences and limitations, the fact remains that U.S. law, when required, has permitted an approximation of investigative detention. This approximation, occurring in the context of a system that technically prohibits it, remains limited and crude—but, when it is needed, one nevertheless sees the straining efforts of a domestic legal system that is stretching beyond the place where its roots long ago fastened it to reach something that it requires.

Accordingly, though the direct impact of international human rights law may be less acute in the United States, one sees that the U.S. legal system generally comports with what that body of law requires. Individuals who are arrested, including terrorist suspects, and detained in the United States are usually presented to a U.S. judicial authority within forty-eight hours of arrest, a period of time that includes a very limited six-hour period during which confessions will not be excluded solely because of delay. This regulation meets the more stringent requirements of Article 9 of the ICCPR, and—though the United States is not a party to the ECHR—it is clear that U.S. practice would also generally satisfy the more permissive standards of Article 5 of the ECHR. Notably, even those instances of prolonged detention of terrorist subjects on naval vessels would likely still comport with the standards set forth in the ECHR due to the ECtHR’s holding in Medvedyev and Others v. France that thirteen days’ detention at sea without judicial oversight did not breach Article 5(3) of the ECHR because it was not “materially possible” to bring the detainees before a judicial authority any quicker.

Use of Extrajudicial or Special Tribunals

Finally, it is worth noting that comparisons among these three countries have also highlighted commonalities in their use of special courts to address terrorism. For instance, France used the alternative procedures of the so-called Military Justice Court (Cour militaire de justice) to judge cases involving Algeria and terrorism, though it ultimately faced judicial resistance from the Conseil d’Etat, which found its procedures lacking, annulled the decree establishing it, and ended its operation. Thereafter, in 1963, the French government replaced the Cour militaire de justice with a State Security Court (Cour de Sûreté de l’Etat). This second version included civilian magistrates as well as military members and allowed for the possibility of an appeal from convictions it rendered. The Cour de Sûreté de l’Etat continued to operate in this form for decades, until it was abolished in 1981. Toward the twilight of this institution, it had come to be viewed as a symbol of political oppression. Thereafter, the French government initially took the view that no special legislation was required to address terrorism.

The United Kingdom, similarly, adopted “Diplock Courts,” which relied upon alternative procedures to judge cases involving terrorism. Such courts faced sustained international criticism, much of which focused on the elimination of the right to a jury trial and the admissibility of certain confessions and testimony. The UK government technically abolished the Diplock Courts in 2007, though the Director of Public Prosecutions retained temporary power to decide if certain exceptional cases should be tried without a jury (most notably in case in which he or she determined that there is a risk of jury intimidation).

The United States, in turn, began to use military commissions after the September 11 attacks. Various efforts were undertaken to create a workable framework for this purpose—but the tension between the U.S. constitutional framework and the idea of a special court quickly became apparent. The U.S. Supreme Court, in Hamdan v. Rumsfeld, held that the initial military commission procedures “contravened certain constraints imposed by the UCMJ [Uniform Code of Military Justice] and the four Geneva Conventions signed in 1949.” In response to that decision, the U.S. Congress enacted the Military Commissions Act of 2006, “which amended the statutory procedures governing military commissions to cure the flaws identified in Hamdan.” The Military Commissions Act of 2006 enumerated thirty war crimes that could be prosecuted by the military commission system, “and conferred jurisdiction on military commissions to try ‘any offense made punishable by this chapter or the law of war when committed by an alien unlawful enemy combatant before, on, or after September 11, 2001.’”

In 2009, Congress passed the Military Commissions Act of 2009, which superseded the 2006 Military Commissions Act and provided detainees with certain additional procedural safeguards. The 2009 legislation authorized the President to establish military commissions to try “alien unprivileged enemy belligerents” for violations of the law of war and other offenses triable by military commissions. As U.S. courts have noted, “the offenses specified in the 2009 MCA are ‘triable by military commission … only if the offense is committed in the context of and associated with hostilities,’” and hostilities are defined as “any conflict subject to the laws of war.” The military commissions, however, have never ripened into an extremely successful venue for the effective prosecution of terrorists.

For all three countries, therefore, experience has demonstrated a tension between liberal democratic values and the use of special courts that utilize procedures that depart from the standard operations of their ordinary domestic courts. This tension (which includes concerns over human rights) has made such courts difficult to maintain in liberal democracies—especially against a backdrop of effective judicial institutions that are more than capable of addressing terrorism using existing laws and procedures. The experience of all three countries, therefore demonstrates that the primary judicial apparatus that must be utilized to address the threat of terrorism is ultimately a country’s ordinary domestic judicial system. Accordingly, planning for counterterrorism efforts should eschew special courts and instead refocus efforts and resources to fortify domestic courts, prosecuting authorities, and attendant institutions.


The withdrawal of military forces from key battlegrounds in the fight against terrorism will greatly limit the supply of effective battlefield solutions, curtailing what can be done both operationally and legally. The future operating environment will increasingly be one in which the law of armed conflict is not the relevant legal framework, forcing counterterrorism practitioners to more frequently find solutions to operational challenges within the framework of criminal justice authorities; thus, the subject of investigative detention and its exploration across divergent legal systems is of practical value for national security practitioners. Such an exploration permits a fulsome understanding of the capabilities, limitations, and processes of international partners, and informs our understanding of how the range of external and exogenous forces (security threats, legal evolutions, etc.) are shaping the legal and national security structures in other parts of the world. It permits us to observe how these dynamic forces are reforming the universe of rights and authorities in ways that can expand or curtail the ability to detain and question terrorist suspects. Peering through the keyholes into this vortex of international law, comparative law, and national security concerns, we are better able to observe important changes and to understand how important legal structures are forming, behaving, and evolving. This insight can help inform decisionmaking relevant to cross-border counterterrorism efforts.

Relatedly, this exploration permits interesting insights into how international law is reshaping legal paradigms. Given that the United Kingdom and France are considered archetypes of divergent legal traditions, one would expect that these countries would sit on opposite sides of a procedural divide, with the common law countries sharing common procedural traits that are dissimilar from their civil law corollaries. As my book demonstrates, however, this is not necessarily true with regard to investigative detention—especially in matters of counterterrorism. Compelled by international legal requirements, modern French law provides a phalanx of protections to detained suspects, such as meaningful access to counsel, rights advisements, the right to remain silent, and so forth. Conversely, catalyzed by counterterrorism concerns, contemporary UK law permits pre-charge detention for investigative purposes for up to four days in ordinary cases and up to fourteen days in terrorism cases, with the concomitant ability to limit the rights of the suspect so that investigators have increased access to the detainee.

These changes are discrete but important departures from the expectations of their respective legal models. Driven by both the demand for effective national security responses and the requirements of international human rights law, we are witnessing a discrete moment of legal convergence, with each legal system taking on elements of its comparative legal analog. The result is an increasing similitude among even the most seemingly divergent systems of the UK and France in which aspects of each system were combined: the detention authority of the inquisitorial model and the protections of the common law model. One even sees the U.S. system, albeit in different ways, straining to facilitate investigative detention in discrete instances. The result is the coherence of domestic and international legal frameworks that, despite their differences, bend toward a common telos and, through the development of somewhat similar legal substructures, permit the detention of terrorist suspects for investigative purposes. Understanding how such tools can operate in accordance with international human rights law and in the context of liberal democracies will be important in the new global security environment.


Dan E. Stigall is the Deputy Chief of Staff and Counselor for International Affairs for the National Security Division, U.S. Department of Justice (DOJ). He is also a Distinguished Professional Lecturer in National Security Law at the George Washington University Law School.